Thorn Cycles Forum

Technical => Transmission => Topic started by: swayzak on March 20, 2011, 03:05:09 pm

Title: Thorne Sterling eccentric bottom bracket adjustment / loose chain ?
Post by: swayzak on March 20, 2011, 03:05:09 pm

Hi

I have the following chain fitted (came with bike, approx. 10 months old):

KMC Z610HX 1/2 Inch x 3/32 Inch Silver Chain for Single and 3 Speeds

My chain came off last week for the first time and, after inspection & consulting manual, I think the chain has stretched.

The bottom bracket is in the "11 o'clock" position (when looking from non chain-ring side), which didn't leave much play for tightening up the chain. I'd have thought the bike would have been setup when built with the bottom bracket around the 3 o'clock position (with optimally tensioned chain) to allow maximum stretch accomodation with eBB adjustment (before having to remove a chain link). Am I misunderstanding ?

Anyway, I turned the eBB to 9 o'clock to tighten chain as much as possible - I think it has helped but there remains a fair amount of vertical play in the chain at rest e.g. about an inch.

I shall watch out for further chain coming-off episodes - if it seems I need to make further adjustments (e.g. turn eBB back to 3 o'clock, remove a link & readjust), is this easy to do ? How would I remove a link with this chain (have never done before) ?


thanks

Title: Re: Thorne Sterling eccentric bottom bracket adjustment / loose chain ?
Post by: Fred A-M on March 20, 2011, 04:04:55 pm

Swayzak

You shouldn't overtighten the chain, it can lead to damage to the RHub.

From your description, an inch play is about right, so in as far as I'm able to understand, there's no need to remove a link.

Cheers

Fred

Title: Re: Thorne Sterling eccentric bottom bracket adjustment / loose chain ?
Post by: swayzak on March 21, 2011, 04:49:59 pm

Thanks

Maybe I'll speak to Thorne regarding removal of links for this chain.

Title: Re: Thorne Sterling eccentric bottom bracket adjustment / loose chain ?
Post by: Blacksail on March 21, 2011, 07:28:31 pm

Swayzak

http://www.thorncycles.co.uk/thornpdf/ThornBikeOwnerManual2Web.pdf

page 9 should answer your questions, goodluck.

Title: Re: Thorne Sterling eccentric bottom bracket adjustment / loose chain ?
Post by: swayzak on March 22, 2011, 08:13:47 am

Thanks

Yes I have that - it's the link removal procedure I need to know now (for the next time the chain stretches too far)  :)

PS T1 - T2 seems to be equal to or greater than the 60mm quoted in that guide (e.g T1 = approx 150mm, T2 = approx 90mm) - even after turning eBB to maximum stretch position ! I've only had the bike for 10 months.